JP2018026353A - Data cable - Google Patents

Abstract

PROBLEM TO BE SOLVED: To achieve good transmission quality of a data cable used in applying the Internet to an automobile.SOLUTION: A data cable 2 has a transmission core 4 with only a single stranded conductor pair or four conductors stranded together to form quad stranding. The transmission core 4 is surrounded by an outer sheath 24 having a high air content. The outer sheath 24 is selectively formed by either a foamed intermediate sheath 26, or at least one spacer element that defines an annular sheath space with free air spaces around the transmission core 4.SELECTED DRAWING: Figure 4A

Description

  The present invention relates to a data cable for transmitting data signals in the high frequency range, for example in the megahertz or gigahertz range, and to a motor vehicle having such a data cable.

  A technology referred to as Ethernet (registered trademark) is known for data transmission, and in particular, its use in automobiles is expanding. In this case, the Ethernet line of an automobile is usually composed of only one pair of conductors. For example, in a normal household equipment line of categories CAT5 and CAT6, usually four pairs are included in one data cable. Incorporated into. In the automotive field, data lines are often implemented without pair shielding. That is, each conductor pair is not shielded. Each conductor pair is usually twisted together. Furthermore, a stranded wire called a four-stranded wire, particularly a star-shaped four-stranded wire, in which four conductors are twisted together is known.

  In such an unshielded line, the high-frequency electromagnetic field also propagates to the outer region, i.e. in particular the sheath surrounding each conductor pair or four strands. Therefore, the sheath affects the transmission quality and transmission loss of the high-frequency data cable.

In this case, undesired transmission of energy from one cable to another due to this transmission characteristic, or radiation of a high-frequency electromagnetic field into the transmission system is also an obstacle. This behavior is known in the art as crosstalk. “Alien-next”, meaning radiation between different service lines or cables in the same cable harness, can be considered an extension of known crosstalk. Transmission systems can only compensate for a limited amount of radiant energy without proper operation.

  Based on the foregoing, it is an object of the present invention to define a data cable having improved transmission characteristics.

  This object is achieved according to the invention by a data cable having the features of claim 1. Preferred developments are disclosed in the dependent claims.

  According to claim 1, the data cable is simply a transmission core formed by a single twisted conductor pair, or alternatively a four-stranded wire consisting of four conductors twisted together, in particular a star. It has a transmission core formed by four twists. In this case, each conductor is composed of a core wire and a conductor insulator surrounding it. In this case, the transmission core is not particularly shielded. In order to reduce the effects of transmission loss and / or external interference, the transmission core is surrounded by a jacket containing a high proportion of air or gas. In this case, the jacket containing a high proportion of air is formed by a foamed sheath or by at least one spacer element that defines an annular sheath space around the transmission core that includes an open air space.

  The jacket is preferably mounted concentrically with respect to the transmission core, so that the jacket and the transmission core are arranged strictly concentrically with respect to each other. Transmission characteristics are favorably affected by this high degree of symmetry.

  This cable is in particular an automotive Ethernet line, usually formed by a single conductor pair, which is directly surrounded by an insulating sheath (outer sheath). Standard plugs for such data cables are usually relatively small and thus require a small cable diameter, ie, an outer sheath diameter in the range of only a few millimeters, for example 3 mm.

  In a preferred embodiment according to the first basic variant, a jacket containing a high proportion of air is placed with the intermediate sheath in the middle to form the outer sheath. In this case, this outer sheath is in particular understood to be the outermost sheath concentrically surrounding the transmission core. Thus, there is no further concentric layer or coating disposed around this outer sheath. A cable whose outer sheath is a termination structure forms a pre-assembled unit. Basically, this pre-assembled cable can be combined with further cables to form a composite cable or cable harness. It is desirable to achieve a high proportion of air by foaming the jacket.

  In this case, this embodiment is based on the basic idea of ensuring the required distance from adjacent data cables, for example by means of this jacket embodied as an outer sheath, and thus by this means, for example The crosstalk effect can be minimized. In this case, this type of problem arises particularly in low-cost applications, for example in the automotive field where expensive shielding means for reducing such effects are omitted.

  Thus, adjacent data cables are maintained at a sufficiently large distance as a result of wearing a jacket containing a high proportion of air. At the same time, the jacket material usage is relatively low as a result of the high air content. The same is true for the weight of the data cable. Overall, the result is that unnecessary consumption of material is avoided and costs are kept low.

  According to one preferred development, the intermediate sheath is embodied as a solid sheath made from a suitable insulating material, for example TPE-S. Desirable mechanical properties, such as tensile strength, for example, can be tuned by solid intermediate sheath embodiments.

  As an alternative, the intermediate sheath is also embodied to contain a high proportion of air and is preferably implemented as a foamed sheath. Thus, in this particular scheme, the two foam layers are embodied as an intermediate sheath and a jacket.

  The intermediate sheath desirably has a wall thickness in the range of 0.3 mm to 1 mm, preferably 0.5 mm. The wall thickness of the outer sheath is preferably in the range of 0.2 mm to 0.8 mm. In particular, the outer sheath has a thinner wall thickness than the intermediate sheath.

  In a particularly preferred development, the jacket is embodied such that it can be easily separated from the intermediate sheath. For this reason, the jacket and the intermediate sheath are preferably made of different materials that are joined only to a weak degree, for example, polar or non-polar materials. Alternatively or additionally, a separating agent, for example in liquid form or otherwise in powder form, in particular in the form of stearate, is introduced between the jacket and the intermediate sheath.

This embodiment is based on the idea that in order to be able to connect the data cable to a standard plug, the jacket is arranged only in the intermediate range between the ends of the cable and the jacket is removed in the end region. Therefore, as a result, there is a possibility of using a data cable having a relatively large outer diameter for transmission extension while holding the standard plug as a whole, thereby enabling a maximum outer diameter of 3 mm, for example Become. As a result, the individual transmission cores of two adjacent data cables in one cable harness can be arranged as far apart as possible. At the same time, the diameter is reduced to the required profile only in the region of the plug.

  Correspondingly, mounting of the plug at the end is also preferably realized. In this case, in the region in front of the plug, the jacket is removed and only the data cable with the intermediate sheath is introduced into the plug.

  In this case, in this embodiment, it is not absolutely essential that the intermediate sheath and the jacket are easily separable from each other. Separation of the jacket in the region of the plug or separation of part of the jacket up to a predetermined remaining final diameter can also be carried out by means of a suitable removal tool, for example by a stripping process.

  In the case of the foaming embodiment, the foam jacket is suitably covered with a thin skin layer on at least one side, preferably on both sides. As a result, the jacket is closed especially towards the outer surface and is no longer open-porous. In this case, the skin layer preferably has a wall thickness of only 0.25 μm to, for example, 100 μm. In contrast, the minimum wall thickness of the foam material of the jacket is in the range of 0.2 mm.

  According to an alternative embodiment to the first basic variant, the jacket according to the second basic variant directly surrounds the transmission core.

  This second basic variant is that a solid sheath is not placed in the very close region of the conductor pair or star-twisted four strands, but instead a jacket containing a high ratio of air / gas is placed. Based on thinking. As a result, the high-frequency electromagnetic field of the signal propagating in the data cable, and the high-frequency electromagnetic field of the signal incident around this vicinity of the jacket, is only slightly disturbed and not attenuated.

  The jacket is also preferably surrounded by an additional outer sheath, in particular directly covered. The outer sheath is preferably made of a solid material, and is preferably made of an HF compatible material. Thus, the jacket is embodied in the form of an intermediate sheath disposed between the transmission core and the outer sheath. The outer sheath serves to protect the influence of the external environment.

  However, in a preferred embodiment, the jacket itself directly surrounding the transmission core forms the outer sheath. Therefore, only a jacket containing a high proportion of air is placed. It is desirable not to form a separate sheath that is concentrically arranged with respect to the transmission core. As a result, good transmission characteristics can be obtained at low material usage.

  In this case, the jacket is particularly preferably formed by at least one spacer element embodied in the form of a hose-like element surrounding the transmission core. In this case, the hose-like element has a free air region, so that an annular space in the form of a sheath, the annular space formed by the hose-like element traps a high proportion of air.

  In this case, the hose-like element is preferably extruded on the transmission core. This allows for simple and cost effective manufacturing.

  The hose-like element is preferably formed by a plurality of (plastic) yarns or twisted yarns joined together to form a mesh, spunbond fabric, or screen-like envelope. In particular, the element is an extruded nonwoven.

  For the above two basic variants, the preferred developments mentioned below apply equally.

That is, the ratio between the relative dielectric constant of the conductor insulator and the relative dielectric constant of the jacket is preferably in the range of 1.4 to 1.8, especially about 1.5. In particular, the conductor insulator has a relative dielectric constant in the range of 2.0 to 2.6, and the jacket has a relative dielectric constant in the range of 1.4 to 1.7. As a result of this measure, an appropriate orientation of the so-called pointing vector pointing inward is realized as in the case of the Goubau line, and as a result, the loss of data transmission as a whole is reduced. The jacket is in particular a foamed sheath.

  Furthermore, the jacket has a wall thickness in the range of at least 0.25 mm to 2.2 mm. In particular, the minimum wall thickness ensures that the high-frequency electromagnetic field that penetrates into the jacket spreads as completely as possible only in the area of the jacket.

  The jacket also preferably includes or is preferably constructed from an HF compatible material. This is especially a nonpolar material. That is, the jacket includes, for example, a plastic such as PE, PP, TPE-S, or FEP. The negative effects of polar materials are also mitigated by a high proportion of air.

In this specification, references to HF compatible materials are generally understood to refer to materials having a low dielectric loss factor, particularly at high frequencies. In particular, the loss factor (for 1 MHz) is in the range below about 20 × 10 ⁻⁴ , in particular below 5 × 10 ⁻⁴ , or in some cases below 1 × 10 ⁻⁴ (according to IEC 60250). ).

  In a preferred embodiment, the jacket itself is embodied as a foamed sheath. As a result of this strategy, a high proportion of air or gas is introduced into the jacket by a foaming process. This greatly improves the transmission characteristics compared to a solid sheath.

  In this case, it is desirable that the jacket has a foaming degree in the range of 25 to 80%. Here, the degree of foaming is understood to be the ratio of the trapped air volume to the material volume.

In addition, the foam jacket may be of a density in the range of 0.3 to 0.75 g / cm ³ or particularly of a relatively heavy material such as FEP in the case of a particularly lightweight material such as PE, PP. In some cases, it has a density in the range of 0.65 to 1.8 g / cm ³ .

  The jacket is preferably composed of a plurality of zones, in particular 2 or 3, zones of plastic foamed with different (height) foams. In this case, it is desirable to realize that the inner zone (in the radial direction) has a higher degree of foaming (smaller density) than the outer zone. This different zone can also form an intermediate sheath and an outer sheath. As a result, the two basic variants are combined with each other.

As an alternative to the embodiment of the jacket as a foamed sheath, the jacket preferably has at least one spacer element that directly surrounds the transmission core and usually has a spacer element that abuts the transmission core. In this case, the spacer element itself is interrupted and has a large air portion and is therefore not embodied as an element in the form of a solid hose-like element or sheath. An outer sheath can be provided around this spacer element, in particular directly covering the spacer element. In this case, this outer sheath is composed in particular of solid material, but there is no need to form an additional outer sheath. There is also the possibility of simply placing the spacer element and / or that the spacer element itself forms a sheath. The spacer element itself is composed of HF compatible material.

  In this case, according to a first variant embodiment, the spacer element is embodied in the form of a hose-shaped element, for example in the form of a (cable) screen or mesh, and is arranged around the transmission core. In this case, the spacer element is preferably embodied in the form of a C screen.

  In this case, the element in the form of a screen or hose has a simply small coverage, preferably in the range below 75%. In particular, the coverage is in the range of 10% to 60%.

  The element in the form of a hose generally comprises a screen mesh formed from (plastic) or twisted yarns, preferably individual plastic yarns, which are bonded together. In this case, the plastic thread is likewise made of an HF compatible material.

  In yet another alternative embodiment, the spacer element is finally embodied in the form of a hose-like spunbond fabric that surrounds the transmission core. In this case, the spunbond fabric is preferably constructed from solid plastic or foamed plastic.

  In this case, the at least one spacer element, in particular the spunbond fabric, is generally desired to be formed by an extrusion process, in particular directly attached to the transmission core by an extrusion process. In this case, the spunbond fabric comprises, in particular, individual plastic twists that form a type of mesh product by a special extrusion process. Such an extruded spunbond fabric is used as a packaging material, for example.

  Basically, other hose-like structures surrounding the transmission core, which have only a small coverage and therefore contain a high proportion of air, can also be used. In this case, in particular, the thickness of the hose-like element and thus the radial extent of the spacer element is in the range of the wall thickness of the jacket as defined above, i.e. in the range of 0.2 mm to 2.2 mm.

  This thickness also applies to the variant embodiments defined below for the spacer elements.

  According to an alternative variant embodiment, the spacer element is in particular at least one twisted yarn composed of a plastic made of HF compatible material, which is wound around the transmission core. Has twisted yarn. In this case, it is desirable that the plastic twisted yarn is embodied so as to have a twist opposite to the twisted direction of the conductor pair or the transmission core. This prevents the twisted yarn from entering the gap between the conductors. The twisted yarn is preferably surrounded by an outer sheath, particularly a sheath extruded in the form of a hose.

  In this case, the suitably extruded spacer element is generally solid or made of a foam material. It is produced, for example, by rotating the extruder or the extrusion head during manufacture, in the case of embodiments as a wound twisted yarn.

  The twist length of the transmission core and the twist length of the wound plastic twist yarn preferably have a ratio of prime numbers to each other. This ensures that periodic interference is avoided.

In an alternative embodiment, the spacer element is part of the sheath and is preferably arranged to project radially inwardly inside the sheath. In this case, it is desirable to have a sufficiently large radial length. Thereby, when viewed in the circumferential direction, a sufficient free space is formed between two successive spacer elements. When viewed in cross-section, the spacer element is embodied, for example, in the form of a semi-circle or triangle, or alternatively in the form of a trapezoid. It is therefore generally tapered in the direction of the transmission core. Thus, according to this embodiment, the spacer element is positioned and held around the transmission core. In this case, it is desirable that the radial length of the spacer element matches the wall thickness of the jacket defined above. It is desirable that it be within a range of 0.2 to 0.8 times the maximum wall thickness of the sheath.

  Furthermore, only a small number of spacer elements are integrally molded to ensure the maximum possible confinement of air. In particular, only 4, 6, or up to 8 spacer elements are arranged distributed around the inner circumference of the sheath. In this case, it is desirable to arrange the spacer elements evenly distributed. From the viewpoint of symmetry, the number of spacer elements is desirably an even number.

  In order to ensure that the transmission core, and in particular only one conductor pair, is centered with maximum accuracy relative to the sheath, the transmission core is rotated and guided relative to the sheath including the integrally formed spacer element. . Thus, the individual conductors are guided so as to extend spirally within the sheath, whereby the conductors are supported periodically on the individual spacer elements, so that they are guided centrally by the spacer elements. Is done.

  In yet another alternative embodiment, the jacket is a hollow hose and the transmission core / conductor pair is guided in a corrugated or zigzag shape rather than extending linearly therein. Including. In this way, in particular, a support point of the transmission core, which is repeated periodically, is formed on the inner wall surface of the hollow hose. Thus, the transmission core abuts only at the apex.

  Hereinafter, exemplary embodiments of the present invention will be described in more detail with reference to the accompanying drawings. Each drawing is a schematic diagram.

FIG. 2 is a cross-sectional view of a data cable according to a first basic variant with an outer foam sheath. FIG. 2 is a side view of the data cable of FIG. 1 including an attached plug. It is sectional drawing of the data cable by the 2nd fundamental deformation | transformation aspect. In this cable, the spunbond fabric directly surrounds the transmission core as a jacket containing a high proportion of air, while simultaneously defining the outer sheath. 3B is a side view of the data cable of FIG. 3A. FIG. It is still another modified embodiment of the second basic modified mode. This variant embodiment comprises a jacket that is foamed directly around the transmission core and has an additional outer sheath. It is still another modified embodiment. In this alternative embodiment, a plastic twisted yarn wound with opposite twists is placed between the transmission core and the outer sheath to form a jacket with a high proportion of air. It is sectional drawing of another embodiment. In this embodiment, a radially inward spacer positioned about the transmission core is integrally formed with the outer sheath.

The data cables 2 described below are all preferably symmetrical signal transmission cables in which a signal is transmitted on one core of a line pair and an inverted signal is transmitted on the other core of the line pair. . The data cable 2 is preferably an unshielded data cable 2 and therefore does not include any shielding treatment and has a relatively simple structure. The data cable 2 of the exemplary embodiment has only a single conductor pair as the transmission core 4. In this case, the conductor pair is composed of two conductors 6 each formed by a core wire 8 and a conductor insulator 10 concentrically surrounding it. The two conductors 6 are twisted together, i.e. twisted together, with a certain twist length.

  The conductor insulator 10 is preferably made of polypropylene, and the core wire 8 is a twisted conductor. The individual wires of this twisted conductor are in particular embodied as copper wires and are preferably tinned.

  As an alternative, the transmission core 4 can be formed by a four-strand assembly, in particular a twisted wire called a star-shaped four-strand. In this stranded wire, two conductors 6 positioned on opposite diagonal lines define a symmetrical data transmission conductor pair. Four conductors 6 are twisted together. The conductors 6 directly contact each other by the conductor insulator 10. In order to ensure the high degree of symmetry required for signal transmission without interference, the filling yarn can be centered.

  Overall, a high degree of symmetry is sought and realized by such an unshielded data cable 2 in order to ensure signal transmission without interference.

  In the first basic variant shown in FIG. 1, the transmission core 4 is first directly surrounded by an intermediate sheath 12, which is subsequently surrounded by an outer foam sheath 14. It is desirable that the data cable 2 does not have another layer. The intermediate sheath 12 is preferably a solid sheath 12. As an alternative, it can be a foamed intermediate sheath 12. Both the intermediate sheath 12 and the outer sheath 14 are preferably attached by an extrusion method.

  The intermediate sheath is made of TPE-S, for example. In the exemplary embodiment, outer foam sheath 14 is constructed from polypropylene.

  The outer sheath 14 forms a jacket with a high proportion of air because it is in foamed form. In this case, the degree of foaming is in particular at least about 50%.

  The outer sheath 14 has a wall thickness w1 in the range of 0.2 to 0.8 mm, preferably about 0.5 mm. The intermediate sheath 12 has an average wall thickness w2 in the range of 0.3 to 1 mm, particularly about 0.5 mm. It is desirable that the wall thickness w1 of the outer sheath 14 is somewhat thicker. In this case, the average wall thickness w2 is understood to be the difference between the radius of the transmission core 4 and the outer radius of the intermediate sheath 12, as can be seen from FIG. In view of the required high degree of symmetry, the intermediate sheath 12 surrounds the transmission core 4 strictly concentrically. In this case, the sheath material of the intermediate sheath 12 also enters the gap between the two conductors 6 during the extrusion process. The outer sheath 14 is also arranged strictly concentrically.

  The entire data cable 2 has an outer diameter d 1 defined by the outer diameter of the outer sheath 14. Furthermore, the intermediate sheath 12 has a diameter d2, and the transmission core has a diameter d3. The transmission core is usually in the range of 1.5 to 2.2 mm, especially about 1.8 mm. The diameter d2 of the intermediate sheath 12 is in the range of 2.8 to 3.4 mm, preferably about 3 mm. The total outer diameter d1 is about 0.8-2 mm, especially about 1 mm, larger than the diameter d2 of the intermediate sheath 12. As a result, the overall outer diameter d1 is about 3.6 to 5.5 mm, preferably about 4 mm as a whole.

  In the following, it will be particularly important that the diameter d2 of the intermediate sheath is equal to the standard outer diameter required for standard plugs in Ethernet lines used in the automotive field.

For example, when attaching the plug 16, which is represented very simply in FIG. 2, firstly only the outer sheath 14 is removed over a range of, for example, several centimeters in the end region, and the data cable 2 is only connected to its intermediate sheath 12. At the same time, it is introduced into the plug 16. In this case, it is desirable that the outer sheath 14 be easily separable from the intermediate sheath 12 for the required mounting operation. This is achieved, for example, by making the two sheaths 12, 14 different materials and / or by providing a separation layer between the two sheaths 12, 14.

  The data cable 2 shown in FIGS. 1 and 2 improves overall signal transmission quality as a result of the placement of the outer sheath 14 containing a high proportion of air and the dimension of the intermediate sheath 12 to a standard dimension of 3 mm. Data cable 2 is made available and at the same time offers the special advantage that standard assembly elements such as plug 16 can be used. In particular, the incidence of the energy of the interference source coming from the outside is at least reduced by the outer sheath 14 and the size and surface of the data cable 2 thus increased. At the same time, the amount of material and additional weight required are kept as low as possible by the outer sheath 14 being a foam. Therefore, the sensitivity for so-called alien-next is reduced.

  The variant embodiment represented in another figure represents a different variant embodiment of the second basic variant, in which a jacket containing a high proportion of air is arranged directly around the transmission core 4.

  In the alternative embodiment of FIGS. 3A and 3B, the jacket simultaneously forms the outer sheath 18. Thus, the entire data cable 2 is simply formed by the transmission core 4 and the outer sheath 18.

  The outer sheath 18 is in particular a hose-shaped element in the form of a spunbond fabric 20 that is extruded onto the transmission core 4. This outer sheath 18 is thus characterized by individual strands intersecting each other and thus embodied in the form of a lattice, for example, and comprising individual strands that enclose a free air space 22 therebetween. In this case, as the material for the spunbond fabric 20, a solid plastic or a foamed HF compatible plastic is used. Such extruded spunbond fabrics are known as packaging materials. It is generated in the extruder by two oppositely rotating perforated disks. In order to form the structure, in particular, two so-called D braid elements extending in opposite directions are joined together at the intersection.

  The conductor 6 of the transmission core 4 is basically also suitable for use without a solid outer sheath. This is utilized by the variant embodiment of FIGS. 3A and 3B. This is because additional protection by a solid outer sheath is not always necessary. At the same time, the outer sheath 18 is embodied as a jacket containing a high proportion of air, so that signal attenuation is relatively low, thus improving data transmission.

  On the other hand, the dimensions of the data cable 2 are substantially the same as the dimensions of the cable of FIG. In this case, the transmission core 4 is embodied in the same manner, and the outer sheath 18 has a diameter d2 equal to the diameter d2 of the intermediate sheath 12 in the variant embodiment of FIG. Thus, the outer sheath 18 of FIG. 3A has a diameter d2 of about 3 mm, so that the data cable 2 conforms to the standard plug 16.

  The spunbond fabric 20 as a whole forms a spacer element. Thus, the spunbond fabric 20 forms a spacer, for example, for the adjacent data cable 2 or for the ground potential (vehicle body) or for other components. Embodiments in which the outer sheath 18 is a spunbond fabric saves material and weight compared to a solid outer sheath.

  In yet another variant embodiment of FIGS. 4A, 4B and 4C, a jacket containing a high proportion of air is additionally additionally surrounded by a solid outer sheath 24, in particular.

  In the variant embodiment of FIG. 4A, a foamed intermediate sheath 26 is mounted concentrically on the transmission core 4 before the transmission core 4 is preferably surrounded by a solid outer sheath 24.

  In FIG. 4B, a plastic twisted yarn 28 is attached to form a jacket containing a high proportion of air. This plastic twisted yarn 28 is helically arranged around the transmission core 4 and thus holds the outer sheath 24 in a position spaced from the transmission core 4. An intermediate space between the transmission core 4 and the outer sheath 24 is formed by a free air space 22. By mounting the plastic twisted yarn 28 having a twist opposite to the twisting direction of the conductor 6, the plastic twisted yarn 28 is reliably prevented from being fitted into the gap between the conductors 6. As a result, the required high degree of symmetry is ensured. Subsequently, the outer sheath 24 is joined as a prefabricated hose on the transmission core 4 to which the plastic twisted yarn 28 is attached. This variant embodiment as a whole allows a very small amount of material usage, while at the same time realizing a high proportion of air in the jacket.

  As an alternative to the embodiment of the plastic twisted yarn 28 as the spacer element, a hose-like element is mounted around the transmission core 4 in a manner not shown in detail, for example as in the case of the spunbond fabric 20. The This can be the spunbond fabric 20 shown in FIG. 3B, or alternatively some other hose-like structure that includes a mesh or free air space 22. In particular, a so-called C screen as a mesh made of plastic yarn is attached. In this case as well, it is desirable to attach the outer sheath 24 in a hose extrusion method or a half hose extrusion method.

  FIG. 4C shows an alternative embodiment in which individual spacer elements 30 are integrally formed with the outer sheath 24 to extend radially inward. In this case, the spacer elements 30 are tapered in the direction of the transmission core 4, so that it is desirable for them to have a rounded tip so that they are in point contact with the conductor 6 as much as possible. In order to form the spacer element 30, a corresponding projection is formed on the extrusion die used to extrude the outer sheath 24. These protrusions remain at the same point during the manufacturing process. At the same time, the conductor pair is rotating due to twisting, so that the rotation of the conductor pair guides the conductor pair precisely to the center of the outer sheath 24. For this reason, the conductor pair cannot slip into the gap in the outer sheath 24.

  In this case, in order to achieve the maximum possible air ratio, only a small number of spacer elements 30 are used, in particular a maximum of 8 and preferably only 4 spacer elements 30. In this case, an even number of spacer elements 30 are used in view of the required high degree of symmetry. For manufacturing equipment, this embodiment can be implemented in a conventional extruder and exhibits a high degree of mechanical stability and good processability, since no additional work steps are required for the incorporation of the plug 16. . In this case, the diameter of the outer sheath 24 is also desirably equal to a standard diameter of about 3 mm.

  Finally, in an alternative variant embodiment (not shown in detail), the outer sheath is a hollow hose in which the twisted conductor pairs are arranged in a corrugated or zigzag shape Can be embodied as a hose. In this manner, the transmission core 4 abuts the outer sheath only at the top of repeated deformation.

In the alternative embodiment described herein, an HF compatible material is selected for each jacket. In an alternative embodiment with a foamed sheath, gas or air is introduced as apparent confinement by either chemical or physical foaming processes. In particular, in the alternative embodiment of FIG. 1, the outer foam sheath 14 further has at least a thin skin layer to resist mechanical stress. This thin skin layer is airtight. In order to produce a foamed sheath, an extrusion line with the possibility of physical foaming or a sheath material containing a foaming agent is used in extrusion.

  The data cable 2 described herein is used as part of an in-vehicle power system for an automobile, for example in a common cable harness with another cable or line.

2 Data cable 4 Transmission core 6 Conductor 8 Core wire 10 Conductor insulator 12 Intermediate sheath 14 Outer sheath 16 Plug 18 Outer sheath 20 Spunbond cloth 22 Free air space 24 Outer sheath 26 Foamed intermediate sheath 28 Plastic twisted yarn 30 Spacer element d1 outer diameter d2 diameter w1 wall thickness w2 wall thickness

Claims (1)

A data cable having a transmission core comprising a single twisted conductor pair or four conductors twisted to form four strands, each conductor being covered by a conductor insulator A data cable, wherein the transmission core is surrounded by a jacket containing a high proportion of air, the jacket being formed by a foamed sheath;
A data cable wherein the jacket is mounted directly around the transmission core and an outer sheath is mounted directly around the jacket.

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